1. Field of the Invention
The present invention relates to a power generator that converts vibration energy of a vibrating member to electrical energy using a power generating element.
2. Description of the Related Art
From the past, with vibrating members (vehicle or washing machine body or the like) that support a vibration source such as an automobile power unit, a washing machine motor or the like, there have been ways devised to reduce the vibration such as by attaching a dynamic damper or the like.
However, to handle the high demand for energy saving in recent times, with Japanese Unexamined Patent Publication No. JP-A-2011-152004 and the like, power generators have been proposed that convert vibration energy to electrical energy. Specifically, with the power generator of JP-A-2011-152004, a piezoelectric vibrating body is constituted by attaching a piezoelectric element to a vibration system for which a mass member is elastically connected to a vibrating member by a spring member, and conversion of vibration energy to electrical energy is performed with the piezoelectric element by deformation of the spring member.
However, with the power generator described in JP-A-2011-152004, the piezoelectric vibrating body is a one-degree-of-freedom vibration system for which the mass member is elastically supported by the spring member, so for vibration input of a frequency that is off from the natural frequency, there is the risk of not being able to generate sufficient deformation of the spring member, and not being able to effectively obtain power.
With JP-A-2011-152004, it was also proposed to realize power generation for vibration input of a broad frequency range by providing a plurality of piezoelectric vibrating bodies with different natural frequencies. However, even with a structure for which a plurality of piezoelectric vibrating bodies is provided in this way, there is a limit to the frequency range for which power can be generated for each of the piezoelectric vibrating bodies, so it was difficult to make it possible to generate electricity for vibration input with a broad frequency range.